Friction shock-absorbing mechanism.



B. S. JOHNSON.

FRICTION SHOCK ABSORBING MECHANISM.

APPLICATION FILED MARA. 191s.

Lwg wfi Patented Apr. 29,1919.

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BRADLEY S. JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO WILLIAM H. MINER, OF CHAZY, NEW YORK.

FRICTION SHOCK-ABSORBING MECHANISM.

Specification of Letters Patent.

Patented Apr. 29, 11919.

Application filed March 4, 1918. Serial No. 220,%5.

To all whom it may concern:

Be it known that I, BRADLEY S. JOHNSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have inventeda certain new and useful Improvement in Friction Shock-Absorbing Mechanisms, of which the following is a full, clear, concise, and exact descript on, reference being had to the accompanying drawings, forming a part of thlS specification.

This invention relates to improvements in friction shock absorbing mechanisms.

Heretofore, in the operation of certain types of friction shock absorbin mechanisms, and more particularly suc mechanisms as employed for friction gears of railway draft riggings, considerable difliculty has been encountered due to scoring or uneven wear of the friction shoes and shell. When such friction gears are manufactured in quantities, it has been found that the majority of the same will wear evenly and uniformly whereas for some reason heretoforeunexplainable, a few friction gears apparently of identical structure and form will Wear excessively at a few points. lBy extended experiments and observations of a number of said friction gears operating under conditions similar to actual service, I have discovered the sources of the difliculties above indicated. Generally stated, the difiiculties arise from the concentration of pressure from the wedge to the friction shoes of the gear on certain parts of the shoes due to slight inequalities in the manufacture of the various parts, which it is impracticable to eliminate in commercial manufacture. As is Well known, friction .gears for railway service are either cast or drop forged and machining is impracticable on account of the excessive cost which would be entailed thereby and although a. high degree of perfection has been obtained in the manufacture of the friction gears with the methods commercially available, it is substantially impossible to obtain absolute uniformity of all the parts.

In the drawing I haveillustrated a well known type of friction gear for railway draft riggings wherein is employed a cylindrical friction shell, three friction shoes ciroularly arranged, a central wedge, anti-friction rolls between the wedge and shoes, two heavy mam springs, a follower for the main springs, and a preliminary spring interposed between sa1d followers and the shoes. From observation, I have determined that the excessive wear above referred to, may be 00- casioned by any one or any combination of three main factors. For instance, it is well known that the main springs of railway draft gears while theoretically of equal capacity for a particular type, vary consid erably from the standard capacity so that, in the type of gear illustrated in the drawmg, it is obvious that if one of the main springs should be of somewhat greater capacity than standard and the other spring of corresponding less capacity than standard, the spring follower would be resisted unequally with a tendency for the follower to tilt when the gear is actuated. This would result in an unbalanced resistance to the friction shoes when the latter engage the follower with consequent concentration of pressure on one of the friction shoes. Also, due to the methods of manufacture necessarily employed, it is possible for one side of a friction shoe to be slightly longer than the other side so that the friction shoe will engage t'he spring follower at one corner and thereby concentrate the pressure on that corner or side of the friction shoe with resulting scoring of the friction shell and excessive wear of the shoe itself. Another condition which may arise results from an application of pressure to the wedge at an angle to the axis of the draft gear. This causes the wedge to tilt from its normal position thereby changing the relation of the three sets of cooperating wedge faces of the wedge and friction shoes which in turn will concentrate the pressure on one or two of the shoes and at one side of the shoes.

The object of my invention is to provide means which will absolutely overcome the possibility of any of the above indicated difficulties taking place and which means may be embodied in the parts now employed in friction gears or shock absorbing mechanisms without any appreciable additional expense.

' Inthe drawing forming a part of this specification, Figure 1 is a part longitudinal, sectional view, art side elevation of a f r1ctiongear suitab e for railway draft riggmgs and showing my improvements in connection therewith. Fig. 2 is an enlarged, detail,

sectional view illustrating more particularly the relation of one wedge face and cooperating friction shoe with the antr-frlctlon roller interposed therebetween and showing also one portion of my invention in connection therewith. Fi 3 1s a plan view of one of the improved friction shoes embodying my.-

,oast friction shell and slgring cage having a cylindrical friction she 10 proper and an integral substantially rectangular spring cage 11, the spring cage 11 being so deslgned as to accommodate a pair of heavy marn springs 12-12. The spr1ngs 12-12 at their outer ends engage a main spring follower 13 having a forwardly extended annular flange 14 which provides aseat forthe inner end of a preliminary spring'15. The spring 15 I at its outer end engages a preliminary spring follower 16 that bears against inwardly extending flanges 17-17 of three circularly arranged friction shoes B-B. Within the friction shoes B is extended a wedge C having wedge faces, as hereinafter described, cooperable with the wedge faces of the friction shoes, there being interposed a series of antifriction rolls D between the shoes and the wedge. A retaining bolt 18 extends through the wedge C, through the follower 16, sprmg 15 and main spring follower 13, said bolt holding the parts in assembled relation and the spring 15 under tension, as will be apparent from an inspection of the drawing. All of the foregoing parts, so far as they are described broadly, are well known and the operation of the friction gear will be apparent to those skilled in the art.

As shown in Fi 6 of'the drawing, the friction shoes B' thereof are elongated on one edge, as indicated at 20-20, one shoe B being elongated on one edge, and the other shoe B on the adjacent edge. The result is, as will be a parent from an inspection of said figure, t at the pressure on the two shoes shown in said figure is concentrated at the two adjacent corners, as indicated at 21-21, where the shoes B en age with the main spring follower 113. his

would result in excessive wear on the adjawhat less than 120.

cent edges of the shoes B'B and also in scoring -of the friction shell at the portions 0 posite to said edges. It is also evident t at a substantially similar condition would arise should the frlction shoes B be made of absolutely equal length on each edge but the spring follower 113 tilted somewhat when t e spring resistance in back of the same is uneven.

In order to avoid the two conditions just above-described in connection with Fig. 6, 1 construct each of my improved friction shoes B as follows: As will be ap arent from inspection of the drawing, eac of the shoes B is of circular form as viewed at its ends or, more strictly speaking, each shoe in transverse section constitutes that portion of an annulus corresponding to an angle of somehis provides the outer cylindrical friction surface 23 to cooperate with th corresponding interior cylindrical surface of the shell. Each shoe is, of course,

provided on its interior with a wedging surface as hereinafter explained. At the inner end of each shoe formed as above described, the same is made convex as viewed from the interlor of the shoe and as clearlyidisclosed in Fig. 3.- This convex surface 22 is, of

.course, of arcuate formation when viewed from the inner end of the shoe. The convex ed e 22 above mentioned insures a substantia ly line contact between the shoe and the flange 14 of the follower 13 at the periphery of the shoe. This line contact is also substantially always at the center of the friction shoe at its inner end.

Thus, with the curved inner edges of the shoes 22 above described, it is apparent that even should the main spring follower 13 tilt somewhatfrom .its correct position, nevertheless th points of contact between the shoes and said follower would remain .at or very close to the centers of the friction shoes at their peripheries and it is impossible to concentrate the pressure on the shoes B near the corners or edges thereof. This results in maintaining the friction shoes with their outer cylindrical friction surfaces 23 in perfect contact with the interior cylindrical friction surfaces of the shell and promotes uniform wearing of the engaging friction neoaoee anti-friction rolls from oscillating to conform with any change in position of the wedge relatively to the shoes. This has resulted in the pressure from the wedge being concentrated at the end of one or more of the friction rolls and consequent concentration of the pressure to the sides of corresponding friction shoe or shoes. As it is evident that the wedge may assume any one of an infinite number of positions relatively to the shoes (within the limits of the clearance between the wedge and the shoes), means should be provided to permit the anti-friction rolls to accommodate themselves to the different conditions which may arise. This I accomplish by maklng each pair of roll seats 26 and 27 on the friction shoes and wedge with opposed convex surfaces, as best illustrated in Fig. 4. That is to say, while the roll seats 26 and 27 are made concave as viewed in Flg. 2., to fit the adjacent rolls, they are convexed longitudinally, as viewed in Fig. 4, to permit the anti-friction rolls to oscillate about axes which are perpendicular to the corresponding pairs of parallel codperating wedge sur faces 24 and 25. Consequently, when the wedge C is tilted or oscillated from its normal position, the anti-friction rolls can adjust themselves thereto while at the same time maintaining a true and perfect line contact with the opposed pairs of parallel wedge surfaces 24 and 25 between which the rolls are mounted. This insures an equal application of pressure from the wedge to all the anti-friction rolls throughout the entire lengths of the latter and thereby uniform pressure from the rolls to the shoes. It will also be apparent tothose skilled in the art that the change involved in the roll seats above described can be made without any appreciable extra cost over the shoes as now manufactured.

Although I have herein shown and described what I now consider the preferred manner of carrying out my invention, the same is merely illustrative and I contem plate all changes and modifications that come within the scope-0f the claims a-ppended hereto.

I claim:

1. In a friction shock absorbing mechanism having a friction shell, friction shoes, a wedge, main spring resistance, and a follower between said resistance and the shoes; means for always insuring transmission of pressure from approximately the center of each shoe at its periphery to said follower in substantially a single line parallel to the axis of the shell, and adjacent the friction surface of the latter.

2. As an article of manufacture, a friction shoe for. a friction shock absorbing mechanism, said shoe having an outer friction surface curved in transverse section, an inner wedging surface, and an inner end edge also curved in transverse section and adapted to engage another member of the mechanlsm, sald inner end edge, at its central portion adjacent the friction surface, extendlng beyond the portions of said end edge at either side of the center to thereby lnsure contact between said shoe and said member at the center of the inner edge of the shoe at a point adjacent the friction surface of the shoe.

3. As an article of manufacture, a friction shoe for a friction shock absorbing mechan1 sm, sa1d shoe, in transverse sectlon, constltuting a part of an annulus and having the exterior surface of the shoe forming a friction surface, said shoe having also an inner wedging surface, the inner end edge of sa1d shoe being convex, the convex edge bemg adapted to engage another member of the mechanism to insure a point of contact between the shoe and said member centrally of the shoe adjacent its periphery.

4:. Tn a shock absorbing mechanism, the comblnation with a friction shell having an interior cylindrical friction surface, main spring resistance, a follower, and a wedge, of friction shoes cooperable with said wedge and shell, said shoes having exterior cylindrical friction surfaces, the inner end edges of said shoes being adapted to engage said follower when the mechanism is actuated, said inner end edges of said shoes having the central portions thereof at the periphcries of the shoes extended beyond the portions on each side of the center of the inner edges substantially as and for the purpose specified.

5. In a friction shock absorbin mechanism, the combination with a friction shell, of friction shoes cooperable therewith, a. wedge, a main spring resistance, and antifriction rolls between the wedge and shoes, said wedge and shoes having parallel cooperating sets of wedging surfaces with which said rolls are adapted to engage, said shoes and wedge having roll seats to hold the latter in proper position; and means on said shoes and wedge to permit oscillation of the rolls about axes perpendicular to the corresponding cooperating sets of wedge surfaces.

6. In a friction shock absorbing mechanism, the combination with a cylindrical friction shell, of three friction shoes cooperable with said shell, a wedge, said wedge and shoes having three sets of cooperating parallel wedging surfaces, an anti-friction roll interposed between each shoe and the wedge, cooperating means on said wedge and shoes to permit the rolls to oscillate about axes fperpendi'milar to the corresponding sets 0 'cooperatin when the wedge istilte with respect to shoes; and a main s ringresistance.

7. As an article 0 manufacture, a fric tion shoe for a friction shock absorbing mechanism, said shoe having an outer friction surface, an inner Wedging surface, and

the

' a roll seat at one end of said wedging surface, said roll seat being convex in longitudinal section. v

-8. As an article of manufacture, a wedge for friction shock absorbing mechanisms, said Wedge having a plurality of wedging wedging surfaces I surfaces and a roll seat adjacent each wedgtion surface, an inner wedging surface, a

roller seat' at one end ofsaid wedgin surface, the rollerseat being convex in iongitudinal section, the inner end of said shoe bein convex and adapted to engage another mem er of the shock absorbing. mechanism.

In witness that I claim the foregoing I 30 have hereunto subscribed my name this 14th day of Feb., 1918.

BRADLEY s." JOHNSON. 

